输水隧洞冻结施工段联合支护结构方案分析与优化研究
发布时间：2018-11-08 18:54
【摘要】：本文以国内某隧洞工程为实例，针对该隧洞冻结施工段拟定联合支护措施，着重分析施工过程中和解冻后隧洞围岩稳定及支护受力规律，对支护结构在长期运行条件下的稳定安全性进行校核分析评价并提出优化或者加强建议。 本文采用三维有限元方法模拟各种加固方式(内衬混凝土、钢筋网、钢支撑、环向钢筋、纵向钢筋等)，并采用接触单元模拟了管片与管片之间以及管片与豆砾石垫层之间的相互作用，考虑可能出现的不同计算条件，对拟定的两种联合支护方案进行结构分析并对多种加强方案进行了分析比选。 研究成果包括： （1）对于现有支护方案一，在极端校核荷载条件和疏松砂岩地勘参数下，不能够保证工程运行安全的要求，需要采取有效注浆等措施提高洞周疏松砂岩弹性模量至100MPa左右，同时加密钢拱架间距为40cm，，以保证长期运行下支护结构的安全。在实测土水压力1.1MPa作为设计荷载的条件下，原疏松砂岩弹性模量对支护结构受力影响较大，取上限值60MPa时方案一能够满足隧洞稳定及支护结构安全要求；而取下限值30MPa时支护结构并不具有设计安全裕度，存在较大风险。建议加密钢拱架间距为40cm，同时建议施工中做好排水措施，有效降低洞周土水压力。 （2）对于现有方案二，在极端校核荷载条件和疏松砂岩地勘参数下，并不能保证满足工程运行安全的要求，而在实测土水压力1.1MPa作为设计荷载的条件下，若疏松砂岩弹模在考虑扰动的地勘参数（20~60MPa）范围内取值，方案二均基本能够满足要求。对疏松砂岩弹性模量的敏度分析结果表明，校核条件下需采用注浆措施提高洞周疏松砂岩弹性模量（建议提高至100MPa左右）等力学指标，并建议采用40cm间距的高强度钢拱架。同时建议施工中做好排水措施，有效降低洞周土水压力。 （4）对比现有两个方案，在疏松砂岩弹性模量取地勘参数下限值30MPa和1.1MPa实测水土压力下，方案二基本能够满足工程要求而方案一不能满足要求，但在极端荷载条件下两种方案均需要加强。考虑到现有方案二较现有方案一在施工中需进行隧洞扩挖，可能不利于工程投资和工期方面的要求，推荐在现有方案一的基础上进行加强支护方案的设计。
[Abstract]:Taking a domestic tunnel project as an example, this paper draws up combined support measures for the frozen construction section of the tunnel, and emphatically analyzes the stability of surrounding rock and the force law of support during construction and after thawing. The stability and safety of the supporting structure under the condition of long term operation are checked, analyzed and evaluated, and suggestions for optimization or strengthening are put forward. In this paper, three dimensional finite element method is used to simulate various reinforcement methods (lining concrete, steel mesh, steel bracing, circumferential steel bar, longitudinal steel bar, etc.). The interaction between segment and pea gravel cushion was simulated by contact element, and different calculation conditions were considered. The structural analysis of two kinds of combined support schemes and the comparison of various strengthening schemes are carried out. The research results include: (1) for the existing support scheme one, under the extreme check load condition and the loose sandstone geological prospecting parameter, can not guarantee the engineering operation safety request, Measures such as effective grouting should be taken to increase elastic modulus of loose sandstone around the hole to about 100MPa and the spacing of infilled steel arch frame is 40 cm in order to ensure the safety of supporting structure under long-term operation. Under the condition of measured soil water pressure (1.1MPa) as design load, the elastic modulus of loose sandstone has a great influence on the stress of supporting structure. When the upper limit value of 60MPa is taken, scheme one can meet the requirements of tunnel stability and support structure safety. However, the support structure does not have the design safety margin when the limit 30MPa is taken, so there is a great risk. It is suggested that the distance between the infilled steel arches is 40 cm, and that drainage measures should be done in construction to effectively reduce the pressure of surrounding soil water. (2) for the existing scheme two, under extreme check load conditions and loose sandstone geological prospecting parameters, it can not meet the requirements of engineering operation safety, but under the condition that the measured soil and water pressure (1.1MPa) is used as design load, If the elastic modulus of loose sandstone is obtained in the range of geological prospecting parameters (20~60MPa) considering disturbance, the second scheme can basically meet the requirements. The results of sensitivity analysis on elastic modulus of loose sandstone show that grouting should be used to improve elastic modulus of loose sandstone around the hole (about 100MPa) under checking condition, and high strength steel arch frame with 40cm spacing should be used. At the same time, it is suggested that drainage measures should be done well in construction to effectively reduce the pressure of soil water around the tunnel. (4) compared with the existing two schemes, under the condition that the elastic modulus of loose sandstone is measured under the lower limit values of geological prospecting parameters 30MPa and 1.1MPa, the second scheme can basically meet the engineering requirements, while the first scheme can not meet the requirements. However, both schemes need to be strengthened under extreme loads. Considering that the existing scheme two needs tunnel expansion and excavation compared with the existing scheme 1, it may be unfavorable to the requirements of project investment and construction period. It is recommended that the design of strengthening support scheme should be carried out on the basis of the existing scheme 1.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV672;TV554
本文编号：2319362
[Abstract]:Taking a domestic tunnel project as an example, this paper draws up combined support measures for the frozen construction section of the tunnel, and emphatically analyzes the stability of surrounding rock and the force law of support during construction and after thawing. The stability and safety of the supporting structure under the condition of long term operation are checked, analyzed and evaluated, and suggestions for optimization or strengthening are put forward. In this paper, three dimensional finite element method is used to simulate various reinforcement methods (lining concrete, steel mesh, steel bracing, circumferential steel bar, longitudinal steel bar, etc.). The interaction between segment and pea gravel cushion was simulated by contact element, and different calculation conditions were considered. The structural analysis of two kinds of combined support schemes and the comparison of various strengthening schemes are carried out. The research results include: (1) for the existing support scheme one, under the extreme check load condition and the loose sandstone geological prospecting parameter, can not guarantee the engineering operation safety request, Measures such as effective grouting should be taken to increase elastic modulus of loose sandstone around the hole to about 100MPa and the spacing of infilled steel arch frame is 40 cm in order to ensure the safety of supporting structure under long-term operation. Under the condition of measured soil water pressure (1.1MPa) as design load, the elastic modulus of loose sandstone has a great influence on the stress of supporting structure. When the upper limit value of 60MPa is taken, scheme one can meet the requirements of tunnel stability and support structure safety. However, the support structure does not have the design safety margin when the limit 30MPa is taken, so there is a great risk. It is suggested that the distance between the infilled steel arches is 40 cm, and that drainage measures should be done in construction to effectively reduce the pressure of surrounding soil water. (2) for the existing scheme two, under extreme check load conditions and loose sandstone geological prospecting parameters, it can not meet the requirements of engineering operation safety, but under the condition that the measured soil and water pressure (1.1MPa) is used as design load, If the elastic modulus of loose sandstone is obtained in the range of geological prospecting parameters (20~60MPa) considering disturbance, the second scheme can basically meet the requirements. The results of sensitivity analysis on elastic modulus of loose sandstone show that grouting should be used to improve elastic modulus of loose sandstone around the hole (about 100MPa) under checking condition, and high strength steel arch frame with 40cm spacing should be used. At the same time, it is suggested that drainage measures should be done well in construction to effectively reduce the pressure of soil water around the tunnel. (4) compared with the existing two schemes, under the condition that the elastic modulus of loose sandstone is measured under the lower limit values of geological prospecting parameters 30MPa and 1.1MPa, the second scheme can basically meet the engineering requirements, while the first scheme can not meet the requirements. However, both schemes need to be strengthened under extreme loads. Considering that the existing scheme two needs tunnel expansion and excavation compared with the existing scheme 1, it may be unfavorable to the requirements of project investment and construction period. It is recommended that the design of strengthening support scheme should be carried out on the basis of the existing scheme 1.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV672;TV554
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